Basically, biofouling/biological fouling is the accumulation of microorganisms, plants, algae, or animals on wetted surfaces. In marine environments, biofouling is a serious problem that leads to immense economic and ecological consequences for maritime and aquaculture activities.
Generally, a remedy to this issue is the application of an antifouling coating. Presently, the traditional antifouling coatings in use causes toxicity to marine ecology and environment, thereby necessitating the development of a nontoxic antifouling coating. Nature has ingenious ways of resolving various issues and has refined them over millions of years. As such, researchers have sought inspiration from the superhydrophobic lotus leaf, but the resolve is not adequate. Fortunately, bio-mimics afford another opportunity for developing versatile materials to combat the problem. Borrowing from the pitcher plant, slippery liquid-infused porous surface (SLIPS) have been developed. Bioinspired superhydrophobic and oil-infused surfaces have thus been recognized as interesting and promising materials for a wide range of applications correlated with water environment. Unfortunately, the best material between the two is yet to be revealed.
In a recent research work published in the journal, Colloids and Surfaces A, Mr. Yibo Ouyang and Dr. Ri Qiu at China University of Petroleum and Luoyang Ship Material Research Institute in collaboration with Dr. Jin Zhao, Dr. Peng Wang at Institute of Oceanology, Chinese Academy of Sciences and Dr. Shugang Hu, Dr. Yan Zhang at Shandong University of Science and Technology presented a study where they considered stainless steel (SS) as the substrate, and tested the superhydrophobic and oil-infused surface based on copper (II) hydroxide matrix with prickly chestnut husk morphology. Their main objective was to find out the most applicable route to prohibit attachment of organisms present in seawater to stainless steel, in order to protect it from both biofouling and biocorrosion.
The research team employed a consecutive approach comprising electrodeposition, oxidation and hydrophobization to achieve superhydrophobicity (SHP) by anchoring dodecanethiol moiety onto copper (II) hydroxide surface. Consequently, by infusing oil phase on the intrinsically superoleophilic/superhydrophobic matrix, SLIPS was realized on the stainless steel.
The authors observed that through the use of bacteria and diatoms as the representative organisms, SLIPS was seen to endow higher inhibition effect to stainless steel than superhydrophobic surface. Additionally, by taking epoxy resin as the fouling agent, the adhesion force was measured, and the results indicated that the low affinity of SLIPS to epoxy resin was due to separation effect from the oil layer.
In summary, the study successfully presented the use of stainless steel as a model substrate for preparing copper (II) hydroxide nanostructure having prickly chestnut husk morphology to lock air and oil phase, leading to superhydrophobic and oil-infused surface. It was seen that both sulfate reducing bacteria and diatoms had good fouling effect on bare stainless steel while as SLIPS performed better biofouling inhibition than superhydrophobic surface. This observation was attributed to the isolation effect of oil film to prohibit the interaction between glutinous secretion from organisms and underneath solid substrate.
Yibo Ouyang, Jin Zhao, Ri Qiu, Shugang Hu, Yan Zhang, Peng Wang. Bioinspired superhydrophobic and oil-infused surface: Which is the better choice to prevent marine biofouling? Colloids and Surfaces A, volume 559 (2018) page 297–304.Go To Colloids and Surfaces A